<p>There is a strong correlation between the desiccation environment and the cracking evolution of expansive clay, which thereby exerts a notable impact on the small-strain stiffness properties of subsoils subjected to dynamic loadings in service. To investigate how desiccation environment affects the shrinkage cracking and small-strain stiffness (<i>G</i>) of intact expansive clays, desiccation test, resonant-column test, and microstructural analyses including computerized tomography (CT) and scanning electron microscopy (SEM) were carried out in series. The results indicate that low humidity environments raise the desiccation rate of expansive clay, arrest the shrinkage deformation, and speed up the development of shrinkage cracks. Besides, the degradation of <i>G</i> is hence enhanced and maximum dynamic shear modulus (<i>G</i>_max) is lowered down. Incremental confining pressure hinders the degradation of <i>G</i>, which is significantly manifested in the cases of low desiccation rates. During desiccation, expansive clay at a lower moisture content or a higher confining pressure records a greater <i>G</i>_max, and at each confining pressure, <i>G</i>_max increases at a low rate initially but shoots up thereafter with the decrease in moisture content, which can be formulated in terms of moisture content and confining pressure. In addition, at each confining pressure, the degradation rate of <i>G</i> decreases initially, followed by a dramatic rise with the progressive drop in moisture content, i.e. there exists an optimum moisture content, at which the degradation of <i>G</i> can be suppressed to the uttermost. This work provides a valuable reference for evaluating the small-strain stiffness degeneration of expansive clay exposed to different desiccation environments.</p>